1. Field of the Invention
The present invention relates to a printing device that performs printing according to print image data transmitted from an upper level device and a method of controlling a printing device.
2. Description of the Related Art
In the related art, a printing system has been known which includes a printing device and an upper level device delivering print data to the printing device as well as instructing the printing device to perform printing. In this printing system, for example, the upper-level device generates a raster image type of print image data by using a raster image processer (RIP), on the basis of print data written in PDL (Page Description Language) that is transmitted from a host device, and transmits the generated print image data to a printing control unit of the printing device (for example, refer to Japanese Patent Application Laid-open No. 2004-287519).
Different from the printing system described above, a printing device provided with a printer controller, a printer engine, and data lines to connect the printer controller to the printer engine is already known (for example, refer to Japanese Patent Application Laid-open No. 2002-254763). In the printing device that is disclosed in Japanese Patent Application Laid-open No. 2002-254763, a control line through which various control information is exchanged between the printer controller and the printer engine is separate from the data lines through which print image data is exchanged, so that a high-speed transmission of data can be realized. In the printing system, the print image data of each color is transmitted in parallel so that the high-speed transmission of data in color printing can be realized.
Furthermore, there is proposed a printing system provided with an upper level device for generating print image data, a printing device for performing a print based on the print image data, and a control line and a data line for connecting the aforementioned units, in which the control line and the data line are separate from each other. In this printing system, a printing controller controls also a data processing controller for controlling a transfer timing of the print image data, as well as a control including a sheet conveyance control for conveying a sheet to be printed.
In the printing system according to the related art, in which the control line and the data line are separated, requires an installation of one buffer memory for storing the print image data for each color on the printer engine, in order to perform a color printing with data lines for each color. On the other hand, in the color printing, a plurality of colors are visually mixed to print an almost full-colored image by performing a plurality of printing for each color on one sheet with adjusting positions for each color printing.
For this purpose, the printer controller is required to control the buffer memory for synchronizing each color data through the control line. Thereby, the control system of the buffer memory may be complicated. Therefore, there is a need to provide a controlling method of buffer memory capable of easily synchronizing each color image data stored in the buffer memory.